1. Field of the Invention
The present invention relates generally to a magnetic record regeneration apparatus and, more particularly, to a method of verifying whether writing (write) and readout (read) functions of a preamplifier circuit operate properly or not, and to a magnetic record regeneration apparatus using the method.
2. Description of the Related Art
Recently, along with sophistication of information processing, ensuring credibility of data is becoming an important element. Especially, in magnetic record regeneration apparatus, the most important function is to verify whether data has been able to be recorded on a recording medium or not.
In fact, when writing, data are recorded onto the recording medium by write currents inverted along with inversion of write data, passing through a magnetic head. A detection circuit in a preamplifier circuit can detect disconnection in circuit wiring of a system for writing and disconnection on the head side.
In other words, as verification means of the write system, the own error detection function of the preamplifier can determine defects of other than the preamplifier (such as defective connections).
However, for failures of the preamplifier itself, for example, output current values, verification means does not exist until now and, therefore, it is problematic that functional decline cannot be detected if write currents is reduced by damages of circuit parts due to ESD (electrostatic destruction) of the preamplifier circuit.
For example, as a characteristic of write currents, in order to perform writing sufficiently, a rising portion of a waveform has an overshoot. Therefore, if the write current is reduced such that this overshoot cannot be obtained due to ESD (electrostatic destruction), this reduction can not be detected.
Therefore, conventionally, by providing verification (verifying readout) processing after write operation, the write operation is guaranteed. As a method of the guarantee, some propositions have been made. For example, in Japanese Patent Application Laid-Open Publication No. 1993-41041, a method is described for deciding whether data are correctly written into a recording medium or not by comparing the write data with the read data.
Also, in Japanese Patent Application Laid-Open Publication No. 1999-16129, a method is described for comparing and deciding read waveforms.
Further, in Japanese Patent Application Laid-Open Publication No. 1993-41041, a method is described for knowing failures beforehand by deliberately deteriorating a read signal processing system for failure prediction.
Further, in Japanese Patent Application Laid-Open Publication No. 1986-10577, a method is disclosed for banning writing beforehand if Write-unsafe is detected when writing is performed in an idle state.
However, all of these methods decrease own access performances of apparatuses and are unrealistic methods which are hardly used.
Further, although Japanese Patent Application Laid-Open Publication No. 2003-15751 discloses an invention for verifying a function of a head amplifier for readout in a magnetic head, descriptions are not made for verifying a write function, i.e., verifying whether data is recorded into the recording medium or not, which is most important function, in first place.